A multichannel tubular device containing ultra-thin walled tubes, permeable to O2 and CO2, will be designed and fabricated for use as an extrapulmonary blood gas exchange device. The product is intended to be inserted into the subject's vena caval system, entering into the right common femoral vein and exiting from the right external jugular vein. Oxygen is passed through the lumina of the hollow tubes while the subject's venous blood flows around the external surfaces of the hollow tubes. Oxygen and carbon dioxide pass across the gas-permeable membrane comprising the walls of the intravenous tubes, increasing the O2 contact and decreasing the CO2 contact of the blood within the subject's vena caval system. In the proposed Phase I of this research and development effort, the design and materials for the EPBGE device will be developed and/or selected, a prototype device will be fabricated, techniques will be developed for its insertion and operation, and its efficacy in transferring O2 to CO2 from circulating blood will be assessed. These performance evaluations will be conducted in vivo using large dogs as the experimental animal. Biocompatibility of the device will be screened by assessing the pathologic effects on the animal, thrombotic and/or embolic sequellae, and hematologic changes in the same animals. If feasibility is demonstrated by this Phase I study, Phase II will be embarked on to further develop and optimize the safety and efficacy of the device by in-depth development and evaluation studies preparatory to Phase III commercialization for the production and clinical utilization of the device. It should have wide clinical applicability to hospitalized patients needing improved oxygenation and carbon dioxide removal.